Hair dye is generally classified into four types, namely, oxidative hair dye, ionic hair dye, temporary hair dye, and others. Among these hair dyes, an oxidative hair dye, which is most widely used at present, is also referred to as a permanent hair dye, and it is mainly constituted with paraphenylenediamine or para-aminophenol that becomes an active reaction intermediate as a result of oxidation by hydrogen peroxide. The active intermediate then reacts with a dye coupler molecule in hair, and it changes to a shampoo-resistant hair dye. However, the oxidative hair dye damages hair, may cause contact dermatitis or latent influence on total body for a long period of time, and may be suspected as mutagenicity or carcinogen. An ionic hair dye is also referred to as a semi-permanent hair dye, and it does not damage hair. However, the ionic hair dye is problematic in term of skin coloration upon dyeing, and the dye is washed off as a result of shampooing operation four to ten times. A temporary hair dye does not damage hair, and skin coloration is overcome by washing. However, the temporary hair dye is washed off as a result of a single shampooing operation.
As another hair dye, there has been proposed a non-oxidative hair dye which contains polyvalent phenol and iron salt (Patent Documents 1 to 3). However, previous non-oxidative hair dye products have required a long dyeing time, and their hair dyeing property and color tone have not been satisfactory.
By the way, a possible cause of the color fading of hair dye may be color fading due to light (ultraviolet light). The aforementioned patent documents describe that an ultraviolet absorbent can be added as necessary. However, there is a problem that, even if an ultraviolet absorbent is mixed into a hair dye for the purpose of protecting hair from ultraviolet light, a majority of the ultraviolet absorbent is rinsed off and its effects are hardly exhibited. Addition of a hydrophobic ultraviolet absorbent has also been proposed. However, the hydrophobic ultraviolet absorbent is problematic in that the direct use thereof causes poor solubility, and in that it is difficult to incorporate it into a composition (Patent Document 4).